// eslint-disable-next-line no-unused-vars
let _Vue = null;
export default class VueRouter {
  constructor(options) {
    this.options = options;
    this.routeMap = {};
    this.data = _Vue.observable({
      current: '/',
    });
  }

  static install(Vue) {
    // 1. 判断当前插件是否已经被安装
    if (VueRouter.install.installed) {
      return;
    }
    VueRouter.install.installed = true;
    // 2. 把Vue构造函数记录到全局变量
    _Vue = Vue;
    // 3. 把创建Vue实例时候传入的router对象注入到Vue实例上
    _Vue.mixin({
      beforeCreate() {
        if (this.$options.router) {
          _Vue.prototype.$router = this.$options.router;
          this.$options.router.init();
        }
      },
    });
  }

  init() {
    this.createRouteMap();
    this.initComponents(_Vue);
    this.initEvent();
  }

  createRouteMap() {
    // 遍历所有路由规则,存贮到routeMap中
    this.options.routes.forEach(route => {
      this.routeMap[route.path] = route.component;
    });
  }

  initComponents(Vue) {
    Vue.component('router-link', {
      props: {
        to: String,
      },
      // 运行时Vue版本写法, 不支持template
      render(h) {
        return h(
          'a',
          {
            attrs: { href: '#' + this.to },
            on: {
              click: this.clickHandler,
            },
          },
          [this.$slots.default]
        );
      },
      methods: {
        clickHandler(e) {
          history.pushState({}, '', '#' + this.to);
          this.$router.data.current = this.to;
          e.preventDefault();
        },
      },
      // 完整版Vue本写法
      // template: '<a :herf="to"><slot></slot></a>',
    });
    const that = this;
    Vue.component('router-view', {
      render(h) {
        const component = that.routeMap[that.data.current];
        return h(component);
      },
    });
  }

  initEvent() {
    // window.addEventListener('popstate', () => {
    //   this.data.current = window.location.pathname;
    // });
    window.addEventListener('hashchange', () => {
      console.log(window.location.hash);
      this.data.current = window.location.hash.substr(1);
    });
  }
}
